This study examines local health departments (LHDs) that are advanced in accreditation and quality improvement (QI) efforts, focusing on barriers and facilitators to sustaining improvements and building a QI culture. Using a mixed-methods approach, quantitative data from surveys of 22 LHDs and qualitative data from 10 follow-up interviews with QI lead staff were analyzed. Survey results indicated high self-reported performance in leadership commitment, employee empowerment, and teamwork (100% each), with lower scores for continuous process improvement (86%), customer focus (72%), and QI infrastructure (64%). Interviews revealed key barriers to sustaining QI included staff turnover, budget constraints, and emergent crises, while facilitators included strong leadership commitment, accreditation, and dedicated resources. Findings suggest that early investment in leadership support and staff time, alongside pursuing accreditation, is critical for LHDs aiming to develop and sustain a culture of QI.